Leonardo Pisano (of Pisa), son of Gugliemo Bonacci, was born in Italy and became a mathematician mostly known as Fibonacci. He grew up in North Africa and learned the Hindu-Arabic system of mathematics from the Moors there. He may have been the first to introduce these advanced (for the times) ideas into European civilization and wrote a book called, “Liber Abacci” or book of the abacus. This book included the series of numbers that is now known as the Fibonacci numbers or Fibonacci series.

The Fibonacci series can be constructed by adding 1+1 to get 2, then continuing to add the last pair in the sequence to get the newest member of the sequence. Add 1+2 to get 3, then 2+3 to get 5 and so on, constructing the following series:
1 – 1 – 2 – 3 – 5 – 8 – 13 – 21 – 34 – 55 – 89 – 144 – 233 – 377 – 610 – 987 and so on… As the numbers in the sequence grow larger, the ratio between any two numbers next to each other gets closer to the golden ratio.